Methods and systems for high dynamic range image projectors

ABSTRACT

Projection systems and/or methods for efficient use of light by recycling a portion of the light energy for future use are disclosed. In one embodiment, a projection display system is disclosed comprising a light source; an integrating rod that receives light from said light source at a proximal end that comprise a reflective surface which may reflecting/recycle light down said integrating rod; of reflecting light down said integrating rod; a relay optical system, said relay optical system further comprising optical elements that are capable of moving the focal plane of the projector display system; and a modulator comprising at least one moveable mirror that reflects light received from the integrating rod in either a projection direction or a light recycling direction.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/516,183, filed Jul. 18, 2019, which is a continuation of U.S. patentapplication Ser. No. 15/540,980, filed Jun. 29, 2017, which in turn isthe 371 national stage of PCT Application No. PCT/IB2015/059957, filedDec. 23, 2015, which claims priority to U.S. Patent Application No.62/142,353, filed on Apr. 2, 2015 and U.S. Provisional PatentApplication No. 62/099,078, filed on Dec. 31, 2014, each of which ishereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to light recycling for projector systemsand, particularly, to systems and methods for High Dynamic Range (HDR)projection systems.

BACKGROUND

Projector systems are now being architected with improvements in dynamicrange. Dual and multi-modulator projector display systems are known inthe art. However, additional improvements are possible in both therendering and the performance of such display systems resulting fromimproved modeling of the light processing in such display systems. Inaddition, as appreciated by the inventors, it would be desirable toincrease the brightness of image highlights for dual/multi-modulationsystems and/or the energy performance for single modulation displaysystems—as well as for dual/multi-modulation display systems.

SUMMARY

Projection systems and/or methods for efficient use of light byrecycling a portion of the light energy for future use are disclosed. Inone embodiment, a projection display system is disclosed comprising alight source; an integrating rod that receives light from said lightsource at a proximal end that comprises a reflective surface which maybe reflecting/recycle light down said integrating rod; and a modulatorcomprising at least one moveable mirror that reflects light receivedfrom the integrating rod in either a projection direction or a lightrecycling direction. In other embodiments, dual and multiple modulatorprojector display systems are disclosed. A first modulator may affecteither a pre-modulated halftone image or may affect a highlightsmodulated image for a desired image to be displayed. A second modulatormay be provided for primary modulation of a desired image.

In one embodiment, a projector display system capable of recycling lightfrom a light source, said projector display system is disclosedcomprising: a light source; an integrating rod, said integrating rodconfigured to receive light from said light source at a proximal end andwherein said proximal end comprises a reflective surface capable ofreflecting light down said integrating rod; of reflecting light downsaid integrating rod; a relay optical system, said relay optical systemfurther comprising optical elements that are capable of moving the focalplane of the projector display system; and a modulator, said modulatorcomprising a moveable mirror, such moveable mirror capable of reflectinglight received from said integrating rod in at least one of a projectiondirection and a light recycling direction wherein said light recyclingdirection is substantially in the direction of the integrating rod.

Embodiments for controlling light-recycling in response to imagecharacteristics are also presented.

Other features and advantages of the present system are presented belowin the Detailed Description when read in connection with the drawingspresented within this application.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments are illustrated in referenced figures of thedrawings. It is intended that the embodiments and figures disclosedherein are to be considered illustrative rather than restrictive.

FIG. 1A depicts a dual modulator projector display system with a lightrecycling module shown schematically and as made in accordance with theprinciples of the present application.

FIG. 1B depicts a single modulation projector display system with alight recycling module shown schematically and as made in accordancewith the principles of the present application.

FIG. 1C depicts a projector display system that comprises lightrecycling modules on a plurality of color channels.

FIG. 2 depicts one embodiment of a light recycling module that sufficesfor the purposes of the present application.

FIG. 3 shows the proximal end of an integrating rod suitable for thepurposes of the present application.

FIG. 4 depicts another embodiment of a dual/multi-modulator projectorsystem where it may be possible and/or desirable to perform lightrecycling in accordance with the principles of the present application.

FIG. 5 depicts yet another embodiment of a projector system where lightrecycling may be possible and/or desirable in accordance with theprinciples of the present application.

FIGS. 6A and 6B depict schematically many possible embodiments forprojector systems that may afford these one or multiple opportunitiesfor light recycling in accordance with the principles of the presentapplication.

FIG. 7A is one possible light recycling control system and/or method fora single modulation projector display system.

FIGS. 7B and 7C depict the response curves and response table,respectively, for individual modulated color response for a conventionalDMD component.

FIG. 8 depicts another possible light recycling control system and/ormethod for a single modulation projector display system.

FIG. 9 depicts yet another possible light recycling control systemand/or method for a single modulation projector display system.

FIG. 10 depicts one possible response table for a light recycling for agiven pattern of illumination

FIGS. 11, 12 and 13 depict three algorithms for effective lightrecycling in a display system for which light recycling is possible.

FIG. 14 depicts one alternative embodiment of a light recycling modulein a dual modulator display system.

FIG. 15 depicts one possible Gaussian spot shape produced by relayoptics as made in accordance with the principles of the presentapplication.

FIG. 16 is another embodiment of a relay optical system as made inaccordance with the principles of the present application.

FIG. 17 depicts one embodiment of the focus group of lenses within therelay optical system of FIG. 16 .

FIG. 18 depicts one embodiment of the coma-correction group of lenseswithin the relay optical system of FIG. 16 .

FIG. 19 depicts one embodiment of a relay optical system that may besuitable for projector systems that may perform light recycling.

FIG. 20 depicts an exemplary plot of number of fibers vs. recyclingefficiency for putative projector display systems.

DETAILED DESCRIPTION

As utilized herein, terms “component,” “system,” “interface,” and thelike are intended to refer to a computer-related entity, eitherhardware, software (e.g., in execution), and/or firmware. For example, acomponent can be a process running on a processor, a processor, anobject, an executable, a program, and/or a computer. By way ofillustration, both an application running on a server and the server canbe a component. One or more components can reside within a process and acomponent can be localized on one computer and/or distributed betweentwo or more computers. A component may also be intended to refer to acommunications-related entity, either hardware, software (e.g., inexecution), and/or firmware and may further comprise sufficient wired orwireless hardware to affect communications.

Throughout the following description, specific details are set forth inorder to provide a more thorough understanding to persons skilled in theart. However, well known elements may not have been shown or describedin detail to avoid unnecessarily obscuring the disclosure. Accordingly,the description and drawings are to be regarded in an illustrative,rather than a restrictive, sense.

INTRODUCTION

In the field of projector and other display systems, it is desirable toimprove both image rendering performance and system efficiency. Severalembodiments of the present application describe systems, method andtechniques to affect these improvements by employing light fieldmodeling for dual, or multi-modulation display systems. In oneembodiment, light source models are developed and used to advantageouseffect. Camera pictures of displayed images of known input images may beevaluated to improve light models. In some embodiments, an iterativeprocess may accumulate improvements. In some embodiments, thesetechniques may be used on moving images to make live adjustments toimprove image rendering performance.

Dual modulation projector and display systems have been described incommonly-owned patents and patent applications, including:

-   -   (1) U.S. Pat. No. 8,125,702 to Ward et al., issued on Feb. 28,        2012 and entitled “SERIAL MODULATION DISPLAY HAVING BINARY LIGHT        MODULATION STAGE”;    -   (2) United States Patent Application 20130148037 to Whitehead et        al., published on Jun. 13, 2013 and entitled “PROJECTION        DISPLAYS”;    -   (3) United States Patent Application 20110227900 to Wallener,        published on Sep. 22, 2011 and entitled “CUSTOM PSFs USING        CLUSTERED LIGHT SOURCES”;    -   (4) United States Patent Application 20130106923 to Shields et        al., published on May 2, 2013 and entitled “SYSTEMS AND METHODS        FOR ACCURATELY REPRESENTING HIGH CONTRAST IMAGERY ON HIGH        DYNAMIC RANGE DISPLAY SYSTEMS”;    -   (5) United States Patent Application 20110279749 to        Erinjippurath et al., published on Nov. 17, 2011 and entitled        “HIGH DYNAMIC RANGE DISPLAYS USING FILTERLESS LCD(S) FOR        INCREASING CONTRAST AND RESOLUTION” and    -   (6) United States Patent Application 20120133689 to Kwong,        published on May 31, 2012 and entitled “REFLECTORS WITH        SPATIALLY VARYING REFLECTANCE/ABSORPTION GRADIENTS FOR COLOR AND        LUMINANCE COMPENSATION”.        -   all of which are hereby incorporated by reference in their            entirety.

One Exemplary Physical Architecture

In general, a projector with a single Digital Micromirror Device (DMD)may tend to have a limited contrast ratio. To obtain a greater contrastratio, two or more DMDs and/or other reflectors (e.g.,MicroElectroMechanical Systems (MEMS)) may be arranged in series. As aDMD may operate as a time-division or pulse-width modulator, operatingtwo or more DMDs and/or reflectors in series—both acting as pulse-widthmodulators—tends to require precise time-division alignment andpixel-to-pixel correspondence of time-division sequencing. Suchalignment and correspondence requirements may be difficult in practice.Thus, in many embodiments of the present application, projector and/ordisplay systems may employ different dual-modulation schemes to affectthe desired performance.

For merely one example, one embodiment of a projector display system mayuse the first modulator (e.g., a first DMD/reflector) as a“pre-modulator” or “premod”—that may spatially modulate a light sourceby means of a halftone image that may be maintained for a desired periodof time (e.g., a frame or a portion thereof). This halftone image may beblurred to create a spatially-reduced-bandwidth light field that may beapplied to a second DMD/reflector. The second DMD/reflector—referred toas the primary modulator—may pulse-width modulate the blurred lightfield. This arrangement may tend to avoid both requirements mentionedabove—e.g., the precise time-division alignment and/or thepixel-to-pixel correspondence. In some embodiments, the two or moreDMDs/reflectors may be frame-aligned in time, and approximatelyspatially frame-aligned. In some embodiments, the blurred light fieldfrom the premod DMD/reflector may substantially overlap the primaryDMD/reflector. In other embodiments, the spatial alignment may be knownand accounted for—e.g., to aid in image rendering performance.

While the present application is presented in the context of a dual,multi-modulation projection system, it should be appreciated that thetechniques and methods of the present application will find applicationin single modulation, or other dual, multi-modulation display systems.For example, a dual modulation display system comprising a backlight, afirst modulator (e.g., LCD or the like), and a second modulator (e.g.,LCD or the like) may employ suitable blurring optical components andimage processing methods and techniques to affect the performance andefficiencies discussed herein in the context of the projection systems.

It should also be appreciated that—even though FIG. 1A depicts atwo-stage or dual modulator display system—the methods and techniques ofthe present application may also find application in a display systemwith only one modulator or a display system with three or more modulator(multi-modulator) display systems. The scope of the present applicationencompasses these various alternative embodiments.

FIG. 1A shows one possible embodiment of a dual/multi-modulatorprojector display system 100 that may suffice for the purposes of thepresent application. Projector system 100 employs a light source 102that supplies the projector system with a desired illumination such thata final projected image will be sufficiently bright for the intendedviewers of the projected image. Light source 102 may comprise anysuitable light source possible—including, but not limited to: Xenonlamp, laser(s), coherent light source, partially coherent light sources.As the light source is a major draw of power and/or energy for theentire projector system, it may be desirable to advantageously useand/or re-use the light, so as to conserve the power and/or energyduring the course of its operation.

Light 104 may illuminate a first modulator 106 that may, in turn,illuminate a second modulator 110, via a set of optional opticalcomponents 108. Light from second modulator 110 may be projected by aprojection lens 112 (or other suitable optical components) to form afinal projected image upon a screen 114. First and second modulators maybe controlled by a controller 116—which may receive input image and/orvideo data. Controller 116 may perform certain image processingalgorithms, gamut mapping algorithms or other such suitable processingupon the input image/video data and output control/data signals to firstand second modulators in order to achieve a desired final projectedimage 114. In addition, in some projector systems, it may be possible,depending on the light source, to modulate light source 102 (controlline not shown) in order to achieve additional control of the imagequality of the final projected image.

Light recycling module 103 is depicted in FIG. 1A as a dotted box thatmay be placed in the light path from the light source 102 to the firstmodulator 106, as will be discussed below. While the present discussionwill be given in the context of this positioning, it will be appreciatedthat light recycling may be inserted into the projector system atvarious points in the projector system. For example, light recycling maybe placed between the first and second modulators. In addition, lightrecycling may be placed at more than one point in the optical path ofthe display system. While such embodiments may be more expensive due toan increase in the number of components, that increase may be balancedoff against the energy cost savings as a result of multiple points oflight recycling.

FIG. 1B depicts one embodiment of a projector display system 100 b thatcomprises a single modulator 106 b. Light source 102 b emits (possiblyunder controller control—not shown) a light beam 104 b may betransmitted through a light recycling module 103 b, as before. Modulator106 b may selectively reflect the light, as desired by controller—andmodulated light 108 b may be transmitted through projector optics 112 band projected onto screen 114 as a finally desired image to be viewed.

FIG. 1C depicts one embodiment of a light recycling module that mayperform light recycling on a plurality of color laser channels (e.g., R,G, and B). As may be seen in this example, the display system maycomprise a red light source (R) that enters into an integrating rod 126(e.g., 124 for B and 122 for G) that may be transmitted (possibly viatotal internal reflectance) to a controllable reflector 120 that maycomprise one or more reflectors that may exhibit a recycle position 120b or a transmit position 120 a. If light is to be recycled, reflector120 b would reflect the laser light back into the integrating rod126—which may reflect within that path multiple times—until thereflector is commanded (via controller, not shown) to transmit position120 a. Light transmitted by reflector 120 a may be directed to a redmirror 128 as shown. In the case of blue light, blue light may becombined with red light at dichroic combiner 130. Similarly, green lightmay be thereafter combined as dichroic combiner 132 and the light maythen be further modulated and/or projected—as simply depicted by opticalelement 120. It will be appreciated that this light recycling module maysuffice for the purposes of a single modulator, dual modulator and/ormultiple modulator display systems as desired.

One Light Recycling Embodiment

FIG. 2 depicts one embodiment of a light recycling subsystem and/ormodule, as may be suitable for the purposes of the present application.As discussed above, this light recycling subsystem/module may be placedin the projector system primarily between the light source 102 and afirst modulator 221. Light from light source 102 may be input to theoptical path via an integrating rod/tube/box 202 (e.g., via a port 201b, as seen in FIG. 3 ). Integrating rod/tube/box 202 may comprise asubstantially reflected surface in its interior, so that light that isincident on its surface may be reflected (e.g., possibly multiple times)until the light is exits its extreme right end 203. Once the light exitsthe integrating rod/tube/box, the light may be placed into an opticalpath that is defined by a set of optical elements—e.g., lens 204, 214and 216 and a set of filters and/or polarizers 208, 210 and 212.

First modulator 221 may comprise a number of prisms 218 a, 218 b and areflector 220. Reflector 220 may comprise a DMD array of reflectors, ora MEMS array—or any other suitable set of reflectors possible that mayreflect light in at least two or more paths. One such path is depictedin FIG. 2 . As may be seen, reflectors 220 direct the light onto theinterface of prisms 218 a and 218 b, such that the light is therebyreflected into lens assembly 222 and thereafter to second modulator 229(e.g., comprising lens assembly 224, prisms 226 and 230 and reflector228). This light may be employed to form the finally projected image tobe viewed by an audience.

However, at certain time during the rendering of the final projectedimage, the full power/energy of the light source 102 may not be needed.If it is not possible to modulate the power of light source 102 (or ifit is difficult or if there is additional opportunity to conservelight), then it may be desired to recycle the light from light source102. In this case, and as may be seen in FIG. 2 , it may be possible toalign reflector 220 from its current position as shown (i.e., where thelight is directed to travel the path down to the second modulator—toposition instead where the light would be substantially reflected backto the integrating rod/tube/box 202, along substantially the same pathas described as traveling from right-to-left direction. In oneembodiment, a recycling system may be able to make parts of the imagebrighter. This may be desirable in circumstances where large parts ofthe screen are dark and some parts are very bright.

In another embodiment, a third (optional) path (not shown) allows thereflectors to direct light from the light source to a light “dump”—i.e.,a portion of the projector system where the light is absorbed. In thiscase, the light is wasted as heat to be dissipated from the projectorsystem. Thus, the projector system may have multiple degrees of freedomwhen it comes to directing the light as desired.

FIG. 3 shows one embodiment of the proximal end 201 (i.e., the endclosest to the light source) that aids in affecting light recycling. Asmay be seen, light may travel through integrating rod/tube/box 202(e.g., via multiple reflections) back to the proximal end 201. Proximalend 201 may further comprise a back portion 201 a—which may furthercomprise a reflecting surface—and a port opening 201 b where light fromlight source 102 may be input into the projector system. Light impactingthe back portion 201 a may be reflected back down the integrating rod202 (possibly multiple times until the reflector(s) at the firstmodulator are directed to transmit the light down to a second modulatoror some other suitable optical path to form the final image). Theexamples of FIGS. 2 and 3 may be considered one example of a lightrecycling module that (like other examples given herein) are capable ofrecycling light at some point in the light pathway through the displaysystem.

FIG. 14 is yet another embodiment of a light recycling module 1400—whichmay serve a module for at least one laser and/or partially coherentcolored light source 1402, 1404, 1406. Light from such a source maytransmit through a first optical subsystem 1408 to condition the lightto be input into integrating rod 1412—which may comprise the reflectingproximal end 1410, such as in FIG. 3 . A second optical subsystem 1414may further condition the light as desired prior to input into a firstmodulator 1416. As with FIGS. 2 and 3 above, this first leg of themodule 1400 may affect a light recycling mode, as discussed.

After first modulation, light may be transmitted through a third opticalsubsystem 1418 prior to input into a second modulator 1420—whichmodulates the light for transmission through a projector opticalsubsystem 1422 to project a final image for viewing.

Highlight Embodiments

In one embodiment, an optional highlights modulator may affectadjustable illumination with a fraction of the available light, unlessit is combined with the pre-modulator. To accomplish this, bothmechanical and/or non-mechanical subsystems and techniques of beamsteering may be employed—e.g., steering portions of the illuminationsource to the various paths in the system using mechanical steering,holograms with spatial light modulators or other spatial modulationmethods may be possible. It may be desired with such a system toincrease efficiency by steering light to where it is desired.

Mechanical beam steering may use a collection of reflective elementswhich can be controlled over a range of motion in the horizontal and/orvertical direction. These reflective elements direct the light reachingthem to the desired areas of the modulators following the highlightmodulator creating controlled non-uniform illumination.

Non-mechanical beam steering methods may use a spatial light modulatorto shift the phase of uniform coherent light reaching the modulator. Thephase shifted light creates a three dimensional light field when imagedthrough a lens. The three dimensional light field can be imaged into atwo dimensional light field with different planes from the collapseddimension imaging with varying sharpness or PSF properties onto one ofthe following modulators creating a two dimensional light field.

Without regard to the manner of implementation, highlights modulationrefers to using a modulator to steer light reaching it to anywhere onthe subsequent modulators. While there can be restrictions, such aspositional range and granularity, the term “anywhere” may still be usedto distinguish highlight modulators from other modulators.

Depending on the number of highlight modulation elements, PSF propertiesand total coverage achievable by the highlights modulator, it may not benecessary in some embodiments to have a pre-mod/first modulator betweenit and the primary/second modulator. In some embodiments, it may bepossible that the highlight modulator may be of such performance as tonot require any modulation (pre or primary) after it.

Highlights to Pre/Prime Relay Optics Control

In some embodiments, it may be possible to adjust the relay optics tocontrol the Point Spread Function shapes of illumination on to thepre-mod/first modulator or primary/second modulator generated by ahighlights modulator. In some embodiments, there may be controls toadjust the Full Width Half Max dimension as well as to control the shapeor tails of the PSFs. It may be desirable to predict, monitor and/ormeasure the resulting performance when light recycling is employed asadditional passes through the integrating rod will change the uniformityand angular diversity of the light which will in turn affect theresulting PSFs.

Pre-Mod/First Modulation Embodiments

In some embodiments, Pre-mod/first modulation may entail the ability tomodulate the light arriving at the pre-modulator on the way to theprimary modulator. In some cases, pre-modulation may be employed toincrease the system contrast. With highlighting, it is possible that thehighlight image may illuminate the pre-modulator in addition to thenon-imaged pre-modulator illumination.

In some embodiments, a suitable pre-mod/first modulator may be a DMD, anLCD, LCoS (Liquid Crystal On Silicon) or other intensity modulator.Regardless of the implementation, pre-modulation may be used to modulatethe light intensity reaching it on to the following modulators. The premodulator elements (e.g., mirrors, pixels, etc.) each influence a fixedlocation on the following modulators, or screen if no additionalmodulation follows the pre modulator. Depending on the number of premodulation elements, PSF properties and total coverage achievable by apre-modulator, it may not be necessary to have a primary modulatorfollow it. It is possible that the pre modulator could be of suchperformance as to not require any modulation (e.g., highlight orprimary) before or after it.

Pre to Primary Modulator Relay Optics Control

This refers to the ability to adjust the relay optics to control thePoint Spread Function shapes of illumination on to the Primary modulatorgenerated by the Highlights or Pre modulator. There are controls toadjust the Full Width Half Max dimension as well as to control the shapeor tails of the PSFs. It is possible to use recycling with thepre-modulator, and it may be desirable monitor, model, predict and/ormeasure the resulting illumination intensity as additional passesthrough the integrating rod will change the uniformity and angulardiversity of the light which will in turn affect the resulting PSFs.

Primary Modulator Embodiments

Primary/second modulation may entail the ability to modulate the lightarriving at the primary modulator on the way to the screen. In someembodiments, this may tend to ensure a resulting quality image with highcontrast, and desired spatial and intensity resolution. In someembodiments, it may be possible that the highlight and/or pre modulatorimages may illuminate the primary modulator, in addition to thenon-imaged primary modulator illumination.

In some embodiments, a suitable primary/second modulator may be a DMD,an LCD, LCoS or other intensity modulator. Regardless of the manner ofimplementation, primary/second modulation may serve to modulate thelight intensity reaching it on to the screen. The primary modulatorelements (e.g., mirrors, pixels, etc.) each influence a fixed locationon the screen. The size and shape of each location should be consistentto form the projected screen image whose overall size and shape will bedetermined by the Projection Optics. Depending on the primary modulatorcontrast range, it might not be necessary to use a highlight orpre-modulator. It is possible that the primary modulator may be of suchperformance as to not require any modulation (highlight or pre) beforeit. It may be possible to use recycling with the primary modulator. Itwould be desirable to understand the resulting illumination intensityboth in level and over time in order to compensate with illuminationadjustment or by changing the signal to the modulator to ensure thedesired image is formed. It is possible to measure this level. It isalso possible to model and predict this level algorithmically.

Other Projector System Embodiments

FIG. 4 depicts another embodiment of a dual/multi-modulator projectorsystem 400 where it may be possible and/or desirable to perform lightrecycling. As may be seen, projector system 400 may comprise one or morelight sources (e.g., 402 a and/or 402 b, or other additional lightsources). In this embodiment, the light source 402 a provides light intoan integrated subsystem/box 404 a that may resemble the embodiment ofFIG. 2A. Light from 402 a may eventually make it to first modulator406—where first modulator 406 may be constructed in substantially thesame way as FIGS. 1A, 1B, 1C and/or 2 (i.e., with reflectors that mayreflect the light back into integrating subsystem/box 404 a. The lightmay then proceed to optical subsystem 408, second modulator 410 andthereafter to projector lens 412 and a final projected image may beformed on screen 414.

However, another opportunity for light recycling may occur with anotherone (or more, in other embodiments) light source 402 b. In oneembodiment, light source 402 b may be employed as another primary lightsource (i.e. to provide a significant amount of light for final images asubstantial amount of the time). In this embodiment, light from 402 bmay be further reflected by reflector 403 such that this light may becombined with the light from 402 a at beam splitter 405—and the combinedbeam forms the final image a substantial amount of the time.

In another embodiment, light source 402 b may be used a lesser amount ofthe time in order to provide highlight illumination within part of theimage. It should be appreciated that reflector 403 may be a singlemirror that is possible moveable (e.g. to take light to a dump oranother recycling subsystem). Alternatively, reflector 403 may be a setand/or an array of reflectors (e.g., MEMS, DMD or the like) to provide afiner control of the additional light from 402 b.

In yet another embodiment, light source 402 b may be optional andintegrating subsystem/box 404 b may have a fully reflective surface atthe end proximal to where light source 402 b might be. In thisembodiment, light may have another path (e.g. inside box 404 b, as wellas box 404 a) in which to recycle light. In another embodiment, it mightbe possible to use a one way mirror for 405. In this case, reflector 403would just be a controllable mirror that may redirect the light into 404b and, thus, reflector 403 may only be necessary to “fold” the systemfor recycling. In such an embodiment, there may be no need to have lightrecycled in 404 a but instead light may be recycled in 404 b. This maybe desirable as the recycling reflector which may not have hole in itfor the light input making it a much more efficient recycler.

FIG. 5 is yet another embodiment for which light recycling may bepossible and/or desirable. Projector system 500 may comprise a lightsource 502 and integrating subsystem/box 504 as previously described.Polarizer 505 may be a controllable polarizer such as an LCD which willpolarize a selectable portion of the light in one orientation. Beamsplitter 506 may be a polarizing beam splitter which will let the lightin one orientation pass straight through as uniform light field 514 toget combined using 516 onto primary modulator 518. The light polarizedin the other orientation gets redirected by 506 as 508. Mirror 510 maybe a mirror to fold the system and get light to either a pre-modulatoror a highlights modulator 512, depending on the design of the system.

The non-uniform light field from 512 then gets combined with 514 using516 to illuminate 518. When 512 is a pre modulator, beam 514 may be usedto provide some base level of illumination less than the first step of512 out of dark for very dark portions of the image 522. Alternatively,when 512 is a highlight modulator, 514 is used to provide the uniformlight level required by image 522 in regions where no light will be inthe non-uniform light field created by 512.

In other embodiments, it may be possible to place a recycling-typeintegrating rod (similar to those described in FIG. 3 ) in between 510and 512 (or in between 506 and 510) and a non-recycling version of anintegrating rod (e.g., without a back reflector) in between 506 and 516.In such an embodiment, it may be desired to remove 504 after 502 inorder to keep the light as a tight beam.

One Schematic Embodiment

FIGS. 6A and 6B depict schematically one or more possible embodimentsfor projector systems that may afford these multiple opportunities forlight recycling. FIG. 6A depicts schematically the processing 600 thatmay be possible with a dual/multi-modulator projector system. Thisprocessing may include light from a variety of laser, coherent orpartially coherent light sources—e.g., where laser light may be pulsed(602) or supplied by laser diodes 604. Such light may be combined andtransported (606) in a variety of architectures and manners (asdescribed in connection with several of the embodiments above). Lightmay then be split (608) into component parts (e.g., 610 through 620) andthis light may be combined and split (622) to serve various functions,such as highlight illumination (628), dump illumination (630), pre-mod(or first modulator) illumination (626) and primary (or secondmodulator) illumination (624).

In one embodiment, adjusting the laser power tends to affect the entiredisplay area uniformly for global dimming. This may be appropriate forsome images and scenes in projector systems where it is possible toadjust the laser and/or light source power. However, in somecircumstances, it may be advantageous at low luminance levels to have acontrollable base level uniform illumination applied directly to thehighlights, pre-mod/first modulator or primary/second modulators.Controlling this type of laser power adjustment will be consideredanother form of global dimming.

In one embodiment employing multiple laser sources (either an individuallaser or group of lasers for each controllable source, or by splittinglasers or groups of lasers into each controllable source) in the displaysystem, it may be possible to spatially arrange them such that each oneaffects a portion of the display area allowing for local dimming. Thismethod is different from the highlights modulator in that these localdimming zones are fixed spatially, where the highlights modulation localdimming zones can be spatially adjustable. It is possible to usemechanical light steering to control the laser power adjustment to eachzone by directing the light reaching the mirror to a spatially orientedfiber or optical component such as a segmented integrating rod whichwill direct the light to a predetermined spatial zone on the modulator.

In such a case, the mechanical light steering device may be consideredpart of the laser power adjustment and not a highlights and/or premodulator, however these systems where the number of individuallycontrollable elements on the mechanical steering is greater than thenumber of spatial zones have the additional advantage of being able tospatially redistribute the illumination from a fixed or variable sourcerather than having to directly vary the source of each zone. The spatialapplication of the laser illumination to the modulators may becontrolled by the illumination optics for each modulator. For globaldimming, illumination by the illumination optics (e.g., lenses,integrating rods, etc.) may be designed to uniformly illuminate themodulator. For local dimming, illumination by the illumination optics(e.g., lenslet arrays, segmented integrating rods, etc.) may be designedto take each light path and spread it across a desired portion of themodulator to create the appropriate PSF.

In an embodiment where the pre-mod/first modulator is anticipated toreceive the majority of the illumination, if light recycling isimplemented, then it may be desirable to have its illuminationadjustable either in splitting or with laser power control, or by usingthe modulators to compensate which may reduce contrast.

Several Schematic Embodiments

FIG. 6B depicts several embodiments schematically of projector systemsthat may affect such processing as noted in FIG. 6A. System 632 mayoptionally provide for highlight illumination 628 to enter into anoptical path 634 to a highlight modulator 636. This light may be eithersent into the pre-mod (or first modulator) light path at 642 via opticalpath 644—or the light may be dumped (638) and possibly recycled at 640.

The pre-mod/first modulator stage may input light at 626 via opticalpath 652. This light may be combined with highlight illumination at thepre-mod/first modulator 646, as described. This light may be either sentto the primary/second modulator (e.g., forming a pre-mod image 654)—orit may be dumped and recycled at 648.

The primary/second modulator (660) may receive light from thepre-mod/first modulator or primary illumination 624 (e.g. via opticalpaths 656, 658 respectively). This light may be sent as a primary image662 to projection optics 664, forming projected image 666 onto aprojection screen (possibly with vibration, if the light source iscoherent or partially coherent) 668 and viewed in an auditorium 670 orthe like. Otherwise, the light may be dumped and recycled at 674.

It will be appreciated that this schematic diagram may support a varietyof possible projector systems and that all of them are encompassed inthe scope of this present application. It may suffice that a projectorsystem architecture may support one or more opportunities for lightrecycling for the purposes of the present application.

Control Algorithms Embodiments

As mentioned, in many times during the projection of an image, a set ofimages or video, it may not be desired to use the full power of thelight source to form the final projected image. In this case, a portionof the light may be recycled many times (substantially indefinitely)until it is needed to form a more luminant image. In addition, asreflector 220 may actually comprise a set (or array) of reflectors, theopportunity to recycle light may be possible on a local dimming basis.In one possible embodiment, it may be possible to employ lightrecycling—on either a global or local dimming basis—when not all theavailable light is needed to form the final projected image—and then useit on a targeted basis, e.g., to project a “highlight” in the finalprojected image. A highlight may be a portion of the image for which itis desired to direct a good deal more luminant energy than itssurrounding part of the image in order to accentuate that portion.

In another embodiment, it may be possible to employ lightrecycling—again on either a global or local dimming basis—in order toboost luminance of an image or scene that is, on average, a brighterimage or scene than the one preceding it. These opportunities may ariseduring illumination of the pre-mod/first modulator stage, orprimary/second modulator stage—as may be seen in FIG. 6B.

In one embodiment, the projector system may make a determination as tohow best to employ light recycling through the controller as itprocesses input image/video data. The decision to recycle may be madeeither on-the-fly as the image data is processed—or in advance, in alook-ahead fashion by a frame, set of frames or scene-by-scene basis. Inanother embodiment, whole video and/or scenes may be analyzed off-lineand the control signals may be sent to the controller as part of anassociated metadata stream, together with the image/video data.

FIG. 7A is one embodiment of a flowchart for performing light recycling.Control system/method 700 may input image data at 702. Based on theresponse curve and/or table (e.g., as shown in FIG. 7B), thesystem/method may calculate the Average Picture Level (APL) for eachIndividually Modulated Color (IMC) of the modulator. As may be seen inthe graph of FIG. 7B, each individual color may exhibit a differentrelative brightness for a given DMD fill percentage. It may be desirableto take into consideration these color difference when performing lightrecycling—so as to eliminate and/or mitigate any tonal visual artifacts.It should be appreciated that the flowcharts of FIGS. 7A and 8 mayassume the recycling generates a uniform field of light—whereas theflowchart of FIG. 9 may account for spatial intensity variation due tothe recycling and employ the tables in FIGS. 7C and 10 . For example,according to the Table depicted in FIG. 7C, an input image may bedivided into a 5×4 array of image regions, and light recycling in eachof the image regions may be adjusted as noted, from 0% to 40%.

Returning to FIG. 7A, at 706, the system/method may determine therelative brightness increase for each IMC. Once accomplished,system/method may instruct the display system to reduce the illuminationsource intensity to the reciprocal of the brightness increase for eachIMC. It should be appreciated that other functional relationships may bepossible and/or desirable between illumination source intensity andbrightness increase—e.g., possibly some inverse relationship of somefunction of brightness increase. Where the term “reciprocal” is usedherein, it will be appreciated that such other embodiments are alsopossible. It is possible to adjust the light source intensity in 708,but in some embodiments, the recycling may remain the same (e.g., thepercentage of recycling may not be changed by the source reduction, justthe absolute value—so as to not put too much illumination onto themodulator). Since light travels fast and even the fastest PWM cycle iscomparatively very slow, the recycling may be considered instantaneousand the resulting illumination level may be achieved right after themodulator switches to its current state

In the case where the system employs DMD(s) as primary modulators (e.g.,modulators which spread out the modulation over several time segments),there may be a modulator state and resulting recycling level for eachtime segment and each one may be calculated and compensated. For systemsthat employ DMD(s) as pre-modulators, there may be just one time segmentas the system may drive them with a half tone binary pattern—which mayonly change once per frame (e.g., in practice it may change it 1-4 timesper frame, but this may be significantly less than the 10's-100's oftime segments for a primary DMD modulator). With embodiments employingLCD and LCoS as primary modulators, these may switch slowly (relative toDMD's) while displaying—so the resulting recycling may be integratedover that time to determine how to compensate.

While the control system/method of FIG. 7A may work in general for anydual/multi-modulator display system, this control may work also in thecontext of a single modulator projector system (e.g., as might beconstructed in the same or similar manner as FIG. 1B). Recycling on theprimary modulator may come from the time sequential nature of the DMD,LCoS and LCD based systems.

FIG. 8 is yet another control system/method (800) for light recycling.Control may start inputting image data at 802. At 804, the system maycalculate the APL for each IMC. The system may then determine therelative brightness increase for each IMC at 806. At 808, the system mayreduce the illumination source intensity to the closest setting to thereciprocal of the brightness increase for each IMC, possibly withoutgoing below that reciprocal value. In one embodiment, it may be assumedthat the system may reduce the light with the modulator but not increaseit—in such a case, it may not be desired that the system may reduce theillumination source below the required level. However, in anotherembodiment (e.g., in the case of a mostly dark modulator image), theopposite may tend to be true (e.g., the system may reduce theillumination and then set the modulator to allow more light to pass). Insuch a case, step 808 may proceed to reduce illumination sourceintensity to the closest setting to the reciprocal of the brightnessincrease for each IMC and still allowing for modulator compensation.

The system at 810 may then decrease the intensity of the image driven tothe modulator to compensate for the difference between the desiredreciprocal of the brightness increase and the setting obtainable withthe illumination source. Alternatively, step 810 may also adjust theintensity of the image driven to the modulator to compensate for thedifference between the desired reciprocal of the brightness increase andthe setting obtainable with the illumination source.

FIG. 9 is yet another embodiment of a control system/method for lightrecycling. However, this control system/method may work well in displaysystems where the light non-uniformity due to recycling may need to beconsidered and/or adjusted, and the illumination intensity control isfine grained or continuous. The system/method 900 may input image dataat 902. At 904, the system may calculate APL for each region of an IMC(i.e., where the image may be divided into different regions). At 906,the system may determine the relative brightness increase for eachregion in each IMC based on experimental statistics. The system maydrive patterns (e.g., certain regions off while the rest are on) to themodulator and observe the distribution of light. Depending on thelocation of the dark region, its recycled light may return to themodulator in a non-uniform fashion. This non-uniformity needs to becompensated for on the modulator.

At 908, the system may reduce illumination source intensity to thereciprocal of the region with the lowest brightness increase for eachIMC. The system may determine the relative brightness increase for eachregion in each IMC, based on the illumination source intensity setting.Then, at 912, the system may decrease the intensity of the image drivento each region of the modulator to compensate for the difference betweenthe desired reciprocal of the brightness increase for that region andthe setting of the illumination source.

Given an input image divided into a 5×4 array of image regions, FIG. 10depicts a partially populated (e.g., the center and corner values arepopulated only by measurement, estimation and/or calculation—theremainder may be similarly filled) example Table for setting non-uniformlevels of light recycling on the modulator given a certain modulatorregional pattern (e.g., as derived as part of experimental statistics).In another aspect, it may be possible to show a pattern and then adjustthe resulting recycling levels based on its characteristics. Forexample, Table 1, shows the luminance characteristics of an imagesegmented into a 3×3 array of image regions (e.g., in each region, itshows whether the average or peak luminance level is above or below apredefined luminance threshold (e.g., 10 nits)). For example, since thebottom right region is OFF (or below the threshold), in an embodiment,as shown in Table 2, most of the light recycling may be performed closerto that area and then drop off for image regions positioned furtheraway. Many such tables, derived by experiment, may be used in 906.

TABLE 1 Luminance characteristics of a test image segmented as a 3 × 3array of image regions ON ON ON ON ON ON ON ON OFF

TABLE 2 Percent of light recycling for a 3 × 3 segmented image as afunction of image characteristics 102% 104% 108% 103% 108% 109% 104%108% 110%

FIG. 11 is one embodiment of an algorithm (1100) for reducingillumination source intensity according to brightness increases. Suchbrightness increases may occur on a individually modulated color basisin some systems.

At 1102, the system may input a desire image for viewing. At 1104, thesystem may calculated the light field desired (or otherwise required) tobe generated by the pre-modulator for each of the individually modulatedcolors (IMC). At 1106, the system may calculate the average picturelevel (APL) for the pre-modulator of each IMC. The relative brightnessincrease may be determined at 1108 for each of the IMCs on its APL. At1110, the system may then reduce the illumination source intensity tothe reciprocal of the brightness increase for each IMC.

FIG. 12 is one embodiment of an algorithm (1200) for reducingillumination source intensity—especially in systems that may employpolarization to project images—e.g., as may be seen in FIG. 5 .

At 1202, the system may input a desired image for viewing. At 1204, thesystem may calculate the amount of light to be diverted directly to theprimary modulator (e.g., such as 514 in FIG. 5 ), possibly for each ofthe IMCs. At 1206, the system may then calculate the light fieldrequired to be generated by the pre-modulator of each IMC. The APL maythen be calculated for the pre-modulator of each IMC at 1208. The systemmay then determine the relative brightness increase for each IMC basedon its APL at 1210. At 1212, the system may reduce the illuminationsource intensity to the reciprocal of the brightness increase for eachIMC. This may also include the amount of light to be diverted directlyto the primary modulator for each IMC. At 1214, the system may thenadjust the polarizer (e.g., 505) to align the polarization into a beamsplitter (e.g., 506) such that a desired amount of light may be diverteddirectly to the primary modulator.

FIG. 13 is one embodiment of an algorithm (1300) that may input imagesthat were generated without the assumption that the display system mayengage in light recycling. In one embodiment, the system may adjust forlight recycling in many possible ways—e.g., take a “EDR Master” gradeand mapping it down to the capabilities of the targeted display whilepreserving artistic intent by way of metadata.

At 1302, the system may input a desired image for viewing. This imagemay have been created assuming that no recycling is/was to beaccomplished. At 1304, the system may calculate the APL for each IMC. At1306, the system may determine the relative brightness increase for eachIMC based on its APL. The system may then provide (or otherwisecalculate) the brightness range that may be achievable for each IMC tothe display management algorithm at 1308. At 1310, the displaymanagement algorithm may generate an image to be displayed based on arecycling range which may be less bright than achievable for each IMCwith recycling—but, possibly, not greater. At 1312, the system may thencalculate a New APL (NAPL) for each IMC. At 1314, the system maydetermine the new relative brightness increase for each IMC based on itsNAPL. Thereafter, the system may, at 1316, reduce the illuminationsource intensity to the reciprocal of the NAPL for each IMC.

Relay Optics for High Dynamic Range Projector Systems

In continued reference to FIG. 14 , there is shown a relay opticalsystem 1418 that is placed in between a first modulator 1416 (e.g., apre-modulator) and a second modulator 1420 (e.g., a primary modulator).Such a relay optical system may be desirable to both reduce the amountof artifacts in the image processing—as well as increasing the contrastof the projected image.

As discussed herein in the context of one embodiment, it may bedesirable for the first modulator/pre-modulator to produce a blurredand/or de-focused image based upon image data values, such as thehalftone image mentioned herein. In many embodiments, it may bedesirable to have a relay optical system that tends to produce auniformly blurred/de-focused image from the pre-modulator to the primarymodulator. In addition, it may be desirable to have a desired, defocusedspot shape for this embodiment.

In many embodiments, the relay optical system may comprise lenses orother optical elements that effectively moves the focal plane, correctsfor any coma, and adjusts the spread (e.g., by creating defocus/blur andadding spherical aberration to some desired amount).

For example, FIG. 15 depicts one possibly desirable spot shape 1502which is substantially Gaussian-shaped—where the x-axis is distance (inmm) and the y-axis is the relative amount illumination (e.g., where ‘1’is maximum illumination and ‘0’ is dark). It should be noticed that, ina system that may provide for light recycling or other systems/methodsof supplying highlight, the illumination may exceed “1” at some time oranother.

In addition to the optical system 1418 of FIG. 14 , FIG. 16 is yetanother embodiment of a relay optical system 1600 suitable for thepurposes of the present application. On either end of relay opticalsystem 1600, there may be disposed two modulators—e.g., 1602 a and 1602b (e.g., as shown here as an unfolded prism systems). First modulator1602 a may be a pre-modulator and second modulator 1602 b may be aprimary modulator, as mentioned further herein.

Light transmitted by first modulator 1602 a may be further transmittedthrough a focus group of lenses 1604, a coma-correction group of lenses1606 and a field flattening/spherical aberration-inducing group oflenses 1608—prior to illuminating the second modulator 1602 b. In manyembodiments, the relay optical system may be substantiallytelecentric—e.g., wherein the chief rays (that is, oblique rays whichpass through the center of the aperture stop) are substantially parallelto the optical axis in front of or behind the system, respectively.

FIGS. 17 and 18 depict embodiments of the focus group 1604 and thecoma-correction group of lenses 1606, respectively. As may be seen inFIG. 17 , light from first modulator 1602 a is transmitted to focusgroup 1604. Focus group 1604 may further comprise a first lens 1604a—which may be a plano-convex lens. Lenses 1604 b and 1604 c may be twolenses comprising plano-convex lenses or lenses comprising a slightmeniscus.

Each of these lenses may be designed to have a desired amount ofspherical aberration that, in combination with defocus, can yield theproper light distribution (as shown in FIG. 15 ) at the image plane,where the primary modulator is located. Multiple weak lenses, ratherthan fewer elements with higher power, will produce the desired amountof spherical aberration more easily. The distances between the lenselements can also contribute to achieving the desired amount of theseaberrations.

As mentioned, the amount of blur and/or de-focusing may be set and/orcontrolled, depending on the distance between lens 1604 a and lens 1604b. In one embodiment, a distance and/or air gap of approximately 5-9 mmmay be suitable to provide sufficient de-focusing/blurring forilluminating the second modulator. Another embodiment of the focusinggroup 1604 may affect the ability to change the focus, and therebyadjust the spot size at the primary modulator, by changing the air spacebetween 2 of the elements. In this regard, the adjustable focus with theelements may also tend to create the desired spherical aberration.

In one embodiment, the projector system may set this distance one timeat the time of manufacture and the lenses may be set on a permanentmount for the working lifetime of the projector system. In anotherembodiment, the distance may be dynamically varied during the course ofoperation. In such an embodiment, one or more of the lenses may bemoveably mounted in the relay optical system wherein the distance may beadjusted as desired according to a controller providing control signalsto the moveable mount.

FIG. 18 depicts that light from the focus group 1604 is transmitted to acoma correcting group 1606. As in several embodiments of the presentprojection system, the fact that light is transmitted between twomodulators that may comprise optical elements that are tilted withrespect to one another (e.g., the two modulators comprising a pluralityof prisms or the like), this may tend to induce a certain amount of comaand/or stigmatism into the transmitted light. Thus, in many embodiments,coma-correcting group 1606 may be placed into the optical path tocorrect for this coma and/or stigmatism. One manner of correctingcoma/stigmatism may be achieved by off-setting the optical axis 1607 ain the first lens 1606 a with respect to the optical axis 1607 b in thesecond lens 1606 b by a desired amount, as may be seen in FIG. 18 . Inone embodiment, both lenses 1606 a and 1606 b may be slightmeniscuses—e.g., where the surface proximal to the light path is slightconcave and the surface distal to the light path is slight convex. Itmay be possible that one or both may be plano-convex lenses.

In addition, the coma-correcting group 1606 may be designed to providecolor correction in the light—e.g., so that the projector system mayemploy multiple color light (e.g., red, green and blue) in such a manneras to provide uniform magnification and avoid the use of any additionalcorrective optical elements. If the positive element is made from crownglass with low dispersion, and the negative element of the group 1606 ismade from a flint glass with high dispersion, then the glasses andelement shape can be selected such that all light wavelengths arefocused nearly the same at the primary modulator. This feature also canprovide for the same magnification for each color, so that in a 3-colorprojector, the optical system of FIG. 16 can be made the same for eachcolor's light path.

Light from the coma-correcting group 1606 may be transmitted to fieldflattening/spherical aberration inducing group 1608. Group 1608 may beemployed to provide additional spherical aberration to provideadditional de-focusing/blurring to the Point Spread Function (PSF—e.g.,substantially Gaussian) for the light transmitted to the secondmodulator.

In some embodiments, it may be possible to have relay optics system thatmay have one, two or three functional groups for different arrangements.For example, one relay optical system may comprise a focus group, acoma-correcting group and/or a spherical aberration inducing group indifferent combinations.

Relay Optical System for Projector Systems Employing Light Recycling

In projector systems that employ light recycling systems as discussedherein, FIG. 19 shows one possible embodiment that comprises a firstmodulator 1602 a, a second modulator 1602 b and a relay optical systemthat may comprise a focus group 2004, a coma-correcting group 2006, anda spherical aberration inducing group 2008. The focus group 2004 and thecoma-correcting group 2006 and the spherical aberration inducing group2008 may function and be set substantially the same as discussed abovein the case without light recycling.

However, in a system that employs light recycling, it may be desirablethat the light from the first modulator 1602 a has a different angle ofincidence to the light path coming into the relay optical system (as isdepicted by the light transmitted from surface 2001 of 1602 a). Tocorrect for this angle of incidence, a prism 2010 may be placed at theproximal side of the second modulator 1602 b. This may be so because thelight exiting the object (premodulator 1602 a) is substantially at anangle of incidence of 36 degrees relative to the premodulator 1602 a (inthis case referenced as the chief ray angle), and the light arrives atthe primary modulator 1602 b at 24 degrees angle-of-incidence. This maytend to cause a loss of symmetry in the optical path that is not seen inthe non-recycling case. The light path (both glass and air) to betraveled by light from all corners of the object plane to the imageplane may be desired to be substantially the same. Where the image planeis found to be tilted relative to the primary modulator 1602 b, a wedgeof glass 2010 may be added to one or more of the prisms in the opticalpath, the shape of such wedge to be determined by optimizing the designtaking into consideration the focus group 2004, coma group 2006, andaberration group 2008.

FIG. 20 depicts the etendue of the light source—e.g., if there aremultiple fibers that are illuminating the optical path. For example, inFIG. 14 , there may be more than one light fiber providing illumination.Light that can be delivered into a small spot or a single optical fibermay be preferable to light that is delivered in a large spot or multipleoptical fibers. FIG. 20 shows the potential trade-off in recyclingefficiency. It may be desirable to provide the maximum possible area ofthe input face of the integrating rod to be covered by reflector ratherthan port.

A detailed description of one or more embodiments of the invention, readalong with accompanying figures, that illustrate the principles of theinvention has now been given. It is to be appreciated that the inventionis described in connection with such embodiments, but the invention isnot limited to any embodiment. The scope of the invention is limitedonly by the claims and the invention encompasses numerous alternatives,modifications and equivalents. Numerous specific details have been setforth in this description in order to provide a thorough understandingof the invention. These details are provided for the purpose of exampleand the invention may be practiced according to the claims without someor all of these specific details. For the purpose of clarity, technicalmaterial that is known in the technical fields related to the inventionhas not been described in detail so that the invention is notunnecessarily obscured.

The invention claimed is:
 1. A projector display system comprising: alight source; a controller, said controller receiving input image dataand sending control signals in response to said input image data; afirst modulator, said first modulator controllable by said controlsignals from said controller, and said first modulator configured toproduce a blurred image based on said input image data; a relay opticalsystem, said relay optical system configured to receive blurred imagefrom said first modulator and further configured to provide a desiredamount of defocusing of the blurred image to provide a plurality ofsubstantially Gaussian spots; and a second modulator, said secondmodulator configured to receive and further modulate said plurality ofGaussian spots to produce an image for further projection, wherein saidrelay optical system comprises a spherical aberration-inducing group oflenses.
 2. The projector display system of claim 1, wherein saidspherical aberration inducing group of lenses further comprises aplurality of lenses to provide additional spherical aberration toprovide a desired point spread function to the light sent to the secondmodulator.
 3. The projector display system of claim 1, wherein saidlight source is one of a group, said group comprising: lasers, partiallycoherent light, colored partially coherent light, LEDs, Xenon lamp. 4.The projector display system of claim 1, wherein said relay opticalsystem is configured to move a focal plane a suitable amount to producesaid desired amount of defocusing.
 5. The projector display system ofclaim 4, wherein said relay optical system further comprises: a focusgroup of lenses; and a coma-correcting group of lenses.
 6. The projectordisplay system of claim 5, wherein said relay optical system issubstantially telecentric.
 7. The projector display system of claim 6,wherein said focus group of lenses further comprises a firstplano-convex lens and a set of second lenses comprising one of a group,said group comprising: plano-convex lenses and lenses comprising aslight meniscus.
 8. The projector display system of claim 7, wherein adesired distance between said first plano-convex lens and said set ofsecond lenses is set to produce said desired amount of defocusing. 9.The projector display system of claim 8, wherein said coma-correctinggroup of lenses at least a first lens and a second lens and wherein saidsecond lens is off-set from an optical axis of said first lens toproduce a desired amount of coma correction.
 10. The projector displaysystem of claim 1, wherein said projector display system furthercomprises a prism proximal to said relay optical system, said prismconfigured to correct for an angle of incidence for the light exitingsaid first modulator.